Vulnerability Discussion

Password complexity, or strength, is a measure of the effectiveness of a password in resisting attempts at guessing and brute-force attacks. If the information system or application allows the user to consecutively reuse their password when that password has exceeded its defined lifetime, the end result is a password that is not changed per policy requirements.

Check

Verify the operating system prohibits password reuse for a minimum of five generations.

Check for the value of the "remember" argument in "/etc/pam.d/system-auth" and "/etc/pam.d/password-auth" with the following command:

# grep -i remember /etc/pam.d/system-auth /etc/pam.d/password-auth

password requisite pam_pwhistory.so use_authtok remember=5 retry=3

If the line containing the "pam_pwhistory.so" line does not have the "remember" module argument set, is commented out, or the value of the "remember" module argument is set to less than "5", this is a finding.

Fix

Configure the operating system to prohibit password reuse for a minimum of five generations.

Add the following line in "/etc/pam.d/system-auth" and "/etc/pam.d/password-auth" (or modify the line to have the required value):

password requisite pam_pwhistory.so use_authtok remember=5 retry=3

Note: Manual changes to the listed files may be overwritten by the "authconfig" program. The "authconfig" program should not be used to update the configurations listed in this requirement.